Acetyl salicyclic acid (aspirin) is a widely used analgesic, antipyretic and anti-inflammatory drug, but it causes bleeding in the upper gastro-intestinal tract following oral administration. In most cases such bleeding is so slight as to be harmless, but it can be a major problem in some patients especially those who regularly take high doses, for example those who suffer from rheumatoid disease.
O-hydroxybenzamide (salicylamide) is also a known analgesic, antipyretic and anti-inflammatory drug. Salicylamide does not appear to cause gastro-intestinal bleeding, but unfortunately suffers from other disadvantages, the most significant being extensive inactivation by various metabolic processes in the gastrointestinal mucosal cells and liver. It appears that inactivation is due to conjugation of the phenolic hydroxyl group with sulphate and glucuronic acid. In man, approximately 1.5 gms of salicylamide must be consumed before the enzymes responsible for this conjugation are saturated and significant quantities of unmetabolised salicylamide pass into bloodstream to exert pharmacological action.
Despite these drawbacks, aspirin and salicylamide are widely used, both singly and in purely physical mixtures.
The salicylamide ester of aspirin was prepared by two routes by Anschutz and Reipenkroger (Ann.(1924) 439,1,pp.5-7) but these authors were concerned only with the chemistry of the substances and its preparation. Certainly the publication contains no hint of the possible pharmacological properties of the ester.